| (19) |
 |
|
(11) |
EP 0 818 762 A3 |
| (12) |
EUROPEAN PATENT APPLICATION |
| (88) |
Date of publication A3: |
|
06.10.1999 Bulletin 1999/40 |
| (43) |
Date of publication A2: |
|
14.01.1998 Bulletin 1998/03 |
| (22) |
Date of filing: 08.07.1997 |
|
| (51) |
International Patent Classification (IPC)6: G07F 7/10 |
|
| (84) |
Designated Contracting States: |
|
AT BE CH DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE |
| (30) |
Priority: |
08.07.1996 JP 177751/96
|
| (71) |
Applicant: Kanekichi Corporation |
|
Shizuoka-ken (JP) |
|
| (72) |
Inventors: |
|
- Takeda, Harumi
Osakasayama-shi,
Osaka (JP)
- Kamijo, Akihiko
Higashichikuma-gun,
Nagano-Ken (JP)
- Wada, Ayao
Ohta-Ku,
Tokyo (JP)
|
| (74) |
Representative: Rackham, Anthony Charles |
|
Lloyd Wise, Tregear & Co.,
Commonwealth House,
1-19 New Oxford Street
London WC1A 1LW
London WC1A 1LW (GB) |
|
| |
|
| (54) |
Coding device, decoding device and IC circuit |
(57) A coding device, a decoding device, and an IC card capable of establishing highly
reliable security are disclosed. A random number determining section 11, using a random
number generating procedure selected with a random number generating procedure selecting
section 10, determines a random number (a first secret key) C according to random
number selecting information. On the other hand, an algorithm selecting section 13
selects a secret key code type of algorithm E according to algorithm selecting information.
A secret key coding section 12, using the random number C and the algorithm E, converts
data to be coded B into a secret key code sentence. After a publicized key coding
section 15 converts the random number C and the algorithm selecting information into
a publicized key code sentence, a combined code sentence forming section 14 forms
a combined code sentence by combining together the secret key code sentence and the
publicized key code sentence.